Graphql结果不使用mongoose填充关联类型中的结果

我尝试在Mongoose中创建带有ObjectId引用的模式，并能够使用Apollo Server通过GraphQL查询它们

我已经定义了一本非常基本的书，作者ObjectId ref在mongoose中就是这样定义的

const { ObjectId } = mongoose.Schema.Types;
const AuthorSchema = new mongoose.Schema({
  name: String
});

const BookSchema = new mongoose.Schema({
  name: String,
  author: [{ type: ObjectId, ref: 'Author' }]
});

  type Author {
    id: ID!
    name: String
  }

  type Book {
    id: ID!
    name: String
    author: Author
  }

  type Query {
    authors: [Author]
    author(id: ID!): Author
    books: [Book]
    book(id: ID!): Book
  }

  input AddAuthorInput {
    name: String!
  }

  input AddBookInput {
    name: String!
    author: ID!
  }

  type Mutation {
    addAuthor(input: AddAuthorInput): Author
    addBook(input: AddBookInput): Book
  }

    addBook: async (_, args) => {
      try {
        const {
          input
        } = args;
        return Book.create(input);
      } catch (e) {
        return e.message
      }
    }

      book: async (_, args) => {
        const { id } = args;
        const result = await Book.findById(id).populate('author').exec();

        console.warn('====== Book query result ======');
        console.log(JSON.stringify(result, null, 2));
        console.warn('====== End Book query result ======');

        return result;

有这样一个graphql模式

const { ObjectId } = mongoose.Schema.Types;
const AuthorSchema = new mongoose.Schema({
  name: String
});

const BookSchema = new mongoose.Schema({
  name: String,
  author: [{ type: ObjectId, ref: 'Author' }]
});

  type Author {
    id: ID!
    name: String
  }

  type Book {
    id: ID!
    name: String
    author: Author
  }

  type Query {
    authors: [Author]
    author(id: ID!): Author
    books: [Book]
    book(id: ID!): Book
  }

  input AddAuthorInput {
    name: String!
  }

  input AddBookInput {
    name: String!
    author: ID!
  }

  type Mutation {
    addAuthor(input: AddAuthorInput): Author
    addBook(input: AddBookInput): Book
  }

    addBook: async (_, args) => {
      try {
        const {
          input
        } = args;
        return Book.create(input);
      } catch (e) {
        return e.message
      }
    }

      book: async (_, args) => {
        const { id } = args;
        const result = await Book.findById(id).populate('author').exec();

        console.warn('====== Book query result ======');
        console.log(JSON.stringify(result, null, 2));
        console.warn('====== End Book query result ======');

        return result;

addBook和book查询的解析器中的变异部分如下所示

const { ObjectId } = mongoose.Schema.Types;
const AuthorSchema = new mongoose.Schema({
  name: String
});

const BookSchema = new mongoose.Schema({
  name: String,
  author: [{ type: ObjectId, ref: 'Author' }]
});

  type Author {
    id: ID!
    name: String
  }

  type Book {
    id: ID!
    name: String
    author: Author
  }

  type Query {
    authors: [Author]
    author(id: ID!): Author
    books: [Book]
    book(id: ID!): Book
  }

  input AddAuthorInput {
    name: String!
  }

  input AddBookInput {
    name: String!
    author: ID!
  }

  type Mutation {
    addAuthor(input: AddAuthorInput): Author
    addBook(input: AddBookInput): Book
  }

    addBook: async (_, args) => {
      try {
        const {
          input
        } = args;
        return Book.create(input);
      } catch (e) {
        return e.message
      }
    }

      book: async (_, args) => {
        const { id } = args;
        const result = await Book.findById(id).populate('author').exec();

        console.warn('====== Book query result ======');
        console.log(JSON.stringify(result, null, 2));
        console.warn('====== End Book query result ======');

        return result;

当我问这个问题时

query book {
  book(id: "xxxxxxx") {
    id
    name
    author {
      name
    }
  }
}

我在author.name中得到null，同时我可以从控制台输出中看到.populate（）能够从Authors集合中获得正确的结果

---

这包括我创建的示例代码

您的mongoose模式设置为每本书返回多个作者：

author: [{ type: ObjectId, ref: 'Author' }]

如果只有一位作者，那么只需执行以下操作：

author: { type: ObjectId, ref: 'Author' }

不能返回GraphQL需要单个对象的数组，反之亦然。如果希望保持mongoose模式不变，则需要将

作者

字段返回的类型更改为

作者列表

：

author: [Author]

---

你是对的，事实上，在mongoose schemaHi中设置作者数组是一个错误！我有一个小问题：如果我也需要获得作者的身份证怎么办？你的问题救了我一天